Subject: Re: CCL:G:Gaussian bug?

From: Guido Germano <[email-masked]>
Date: Sun, 13 Jul 1997 17:02:55 +0200 (MDT)

On Fri, 11 Jul 1997, M. Nicklaus wrote:

> > Find enclosed a Gaussian 94 input file with a simple Hartree-Fock run.
> > On a SGI Indigo 2 (Gaussian 94 Rev. D.4) its first SCF reads
> > SCF Done:  E(RHF) =  -1090.96251553     A.U. after   11 cycles
> > while the SAME input file yields on an IBM (Rev. B.3) and a DEC (Rev. D.4)
> > SCF Done:  E(RHF) =  -1086.47515931     A.U. after    3 cycles
> 
> I am running your exact same input file on an Intel
> Pentium Pro 200 MHz machine, running RedHat Linux 4.1
> (kernel v. 2.0.27), using Gaussian 94, Rev. E.1.
> Here are the first two SCF's:
>  SCF Done:  E(RHF) =  -1086.46226785     A.U. after   14 cycles
>  SCF Done:  E(RHF) =  -1086.46242745     A.U. after    8 cycles
>
> What were your final energies after optimization?

Marc, thank you for running this input file on yet another platform with yet
another revision of Gaussian 94, confirming thus that the correct energy is
around -1086.5 and not -1091.0 atomic units. I must apologize because the
very first SCF on the IBM yielded

SCF Done:  E(RHF) =  -1086.47487935     A.U. after   14 cycles

and not, as I wrote, -1086.47515931     A.U. after    3 cycles,

which is the first SCF of the first restart file (it could be guessed also
from the small number of cycles needed to reach self-consistency: 3 instead
of 14, thanks Noj). I restarted the optimization twice, and stopped it after
a total of 44 steps, because there were no significative changes.
The lowest energy, reached at steps 28, 33, 37 and 41, was -1086.47517580.
It surprises me that the first SCF on the Pentium differs after the second
decimal figure from those on the IBM and the DEC, which were identical in
spite of different g94 revisions. However, that's nothing compared with the
4.5 hartrees difference with the SGI...
I didn't receive any answer from Gaussian, Inc. so far, nor any decisive hint
from the CCL folks yet. Below I enclose the list of the energies at every
optimization step.

Regards, and thanks to Nathaniel Malcolm and Marc C. Nicklaus for answering.

_____________________________________________________________________________

Guido Germano                          PhD student in Computational Chemistry

Dipartimento di Chimica e Chimica Industriale    e-mail [email-masked]
Universita` di Pisa                         http://www.dcci.unipi.it/~germano
Via Risorgimento 35                          finger [email-masked] 
I-56126 Pisa                     phone +39-50-918.266, .295 or .239, fax .260
_____________________________________________________________________________

g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47487935     A.U. after   14 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47493464     A.U. after    7 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47131315     A.U. after    8 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47502780     A.U. after    8 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47479785     A.U. after    7 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47497507     A.U. after    8 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47510545     A.U. after    6 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47501048     A.U. after    8 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47517654     A.U. after    7 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47514597     A.U. after    6 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47516223     A.U. after    5 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47515896     A.U. after    5 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.47515784     A.U. after    2 cycles
g94_pdtbuB1.out: SCF Done:  E(RHF) =  -1086.28464749     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.28464749     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47517564     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47515928     A.U. after    3 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47515786     A.U. after    2 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.28462806     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47517587     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47515933     A.U. after    3 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47515786     A.U. after    2 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.28492972     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47517581     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47515931     A.U. after    3 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47515786     A.U. after    2 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.28489904     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47517580     A.U. after   10 cycles
g94_pdtbuB2.out: SCF Done:  E(RHF) =  -1086.47515931     A.U. after    3 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47515931     A.U. after    3 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47515786     A.U. after    2 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.28488924     A.U. after   10 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47517580     A.U. after   10 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47515931     A.U. after    3 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47515786     A.U. after    2 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.28488959     A.U. after   10 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47517580     A.U. after   10 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47515931     A.U. after    3 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47515786     A.U. after    2 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.28488960     A.U. after   10 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47517580     A.U. after   10 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47515931     A.U. after    3 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.47515786     A.U. after    2 cycles
g94_pdtbuB3.out: SCF Done:  E(RHF) =  -1086.28488959     A.U. after   10 cycles